Shouting at the ocean with pebbles in my mouth since 2008. The subjects of this blog include forensics, the war-on-terror detainees, the Duke lacrosse case, the Knox/Sollecito case, and the academic world as it intersects the political. It will sometimes examine issues of particular interest to Wilmington, NC and the University of North Carolina at Wilmington.

Saturday, January 30, 2010

Meredith Kercher’s Bra Clasp

Part V in a series on the Knox/Sollecito case

Meredith Kercher’s bra clasp was separated from her bra, presumably by the murderer.The first problem with the bra clasp in this case is the fact that it was not collected as evidence until about 47 days after the crime, on 18 December 2007.This might not matter if the crime scene had been secure.However, someone had moved the clasp had from its original location (by a meter in some estimates).Someone had broken into the house on two separate occasions in early 2008, after the clasp was in police custody.The lack of control over the bra clasp alone might be enough to disqualify it as evidence.

The glove might have touched the same door or door handle that Raffaele Sollecito used when he attempted to break the door down after Meredith’s murder.This is one possible route of secondary DNA transfer.In addition, note how it was treated in a second video:

The clasp should have been handled with disposable tools.Moreover, the clasp is being passed to and fro unnecessarily, and even put on the ground, both of which increase the likelihood of contamination.One wonders why the clasp is being put on such an elaborate display.

The mixture of DNA

The clasp had Meredith’s profile as the strongest component.A relatively weak component (200 relative fluorescence units) appears to be Raffaele’s DNA.There are reports of DNA from at least three other people (http://www.dailymail.co.uk/news/article-1234298/Amanda-Knox-The-troubling-doubts-Foxy-Knoxys-role-Meredith-Kerchers-murder.html

The 19 November 2009 letter coauthored by Drs. Hampikian and Johnson said, “Transfer of Raffaele’s DNA to the clasp could have occurred through several innocent means as a result of his DNA being in the apartment or via Amanda’s clothing or belongings.DNA testing cannot determine how biological material was deposited onto an item of evidence: whether by direct deposit, or by secondary transfer through an intermediary. DNA testing cannot determine how long biological material may have been on an item, or whether contamination occurred during collection.”

The presence of a mixture leads to several questions.First because I cannot envision how so many people could have handled the bra clasp directly, I think that indirect transfer of DNA is the more likely explanation.Second, it is difficult to see why the three individuals who deposited DNA on the clasp should not be considered potential suspects.Third, suppose that the police had taken other dusty items into evidence at the same time as the bra clasp.If these had been utterly clean of DNA, the results on the clasp would carry more weight.From what I can gather, no such items were taken into custody on the same day.

The lack of other DNA

At a pretrial hearing Mr. Sollecito’s defense team argued that the lack of his DNA on the bra itself is significant (http://www.telegraph.co.uk/news/3255101/DNA-on-Meredith-Kerchers-bloodied-bra-was-due-to-lab-contamination-claims-Sollecito.htmlhttp://www.telegraph.co.uk/news/3255101/DNA-on-Meredith-Kerchers-bloodied-bra-was-due-to-lab-contamination-claims-Sollecito.html), “But defence lawyers used a mannequin's bust and a white bra to argue that it would be impossible for Mr Sollecito's DNA only to have ended up on the tiny clasp and not the rest of the bra if he had touched it or handled it.”

The Hampikian/Johnson open letter said, “Neither Raffaele Sollecito’s nor Amanda Knox’s DNA was found on: the remainder of the bra that was found with the victim, other items of victim’s clothing, objects collected from the room where the victim was found, or in samples from the victim’s body. These evidentiary samples were all collected the day the body was discovered.”

The lack of Sollecito’s or Knox’s DNA on anything in Meredith’s room except the bra clasp is hard to square with an attack that the prosecution claims to have lasted at least 20 minutes.

Conclusions

The main issues I have with the clasp are that it must have been handled by at least one unknown person, that it picked up dust during the 47 days, and that there are deposits of DNA from other individuals on it.

The Johnson/Hampikian letter deserves the last word: “Handling and movement of this sample has compromised its probative value. The laboratory results for this sample cannot reliably be interpreted to show that the DNA of Raffaele Sollecito was actually on the bra clasp at the time of Meredith Kercher’s murder, and it does not establish how or when this DNA was deposited or transferred.”

9 comments:

Anonymous
said...

The evidence seems to indicate that the bra was removed sometime after Meredith was killed based on the strap's outline in blood at the original position she was in before the 'staging' of the body. Raffaele's DNA was not found on the bra itself and from the blood splatter evidence it also seems pretty clear that the bra was on when Meredith was killed. If you accept that the DNA on the clasp was not the result of contamination then it most likely occurred during the 'staging' of the murder scene. If Sollecito pulled up on the clasp so Amanda could get a knife under it to cut it loose might explain it as well as the 'double DNA knife' if that was used to cut the bra clasp off (Meredith's DNA transferred from the bra clasp to the knife but no blood on the knife).

Again, I see it as highly unlikely that knife was the murder weapon and the fact that Raffaele's DNA was found on the clasp could have easily come from contamination or a scenario such as the one I suggested.

It does appear that the jury in this case put much more emphasis on the DNA of the knife and bra clasp than they possibly should have, personally I think the circumstantial evidence is far more convincing but still leaves me with a lot of reasonable doubt. I guess the jury report will give us a better idea of their thinking.

Chris,Once again I appreciate your insight on this issue.In the video I noticed a flashlight as another possible cause of contamination.I understand that at the trial the reason for other unkown persons' Dna was the the result of transfer in a washing machine? Is that possible?TM

Yes, I wondered about the flashight as a source of contamination also. With respect to the laundry issue, I have heard that argument, and I cannot convince myself that I accept it. If dirty clothes come into contact, I can certainly see how DNA might be transferred. One would anticipate that laundry detergent would release skin from clothing, so having clean clothes intermingle shouldn't transfer DNA. Maybe if the bra were folded on a table that someone else touched there might be transfer, or if someone else folded the bra strap, but... I'll see if I can turn up more information.

A fairly obvious possible source of contamination for the bra clasp would surely have to be Amanda's lamp, which was left in the room at some stage. If someone (whether the attacker, or police) had used it or handled it, and Raffaele had been the last one to use it prior to that, a few of his skin cells could easily have ended up in the room and then onto the bra clasp at a later stage. There's even photographic evidence that the lamp was moved onto the desk, just above the bra clasp.

I'm not sure how much weight the jury put on the knife and bra clasp. Were they the determining factor in a verict of guilty or were they just two pieces of many pieces of evidence submitted? Would the verdict have been the same without those two pieces of evidence?

Many have trouble with the bra clasp because of the 6 week delay in collection and the knife was considered with having merit because it was compatible with one of the wounds on Meredith and Sollecito's response concerning Meredith's DNA on the knife. Neither pieces of evidence are smoking guns, though.

I wonder: does the Italian definition concerning DNA transfer/contamination differ from the US definition? Forensic scientists in Italy say that transfer is not easily done, you must press, DNA does not fly around and attach itself to objects. US says transfer is easily done, dust (I guess that would be skin cells?) which had been present before a crime can attach itself to objects thus making testing results suspect.

I'm not sure I am phrasing this correctly but it appears one group says transfer is not so easy and another group says it is.

The forensics are a substantial part of the case and whether they hold up on appeal remains to be seen. Much will depend on the judge's report and the importance placed on the various pieces of evidence.

Here is a link to the testimony of Professor Adriano Tagliabracci, director of the Forensic Institute of Ancona and president of the Italian Association of Forensic Genetics, who testified for the defense:

http://abcnews.go.com/International/US/story?id=8118652

"'The clasp goes from one scientist to another, and we don't see gloves being changed. We then see it being put on the floor and picked up again. These procedures are all wrong,' Tagliabracci testified.'By not changing gloves and by touching other objects, cross-contamination of DNA is highly possible,'' he said."

If the transfer were due to somehow sharing laundry facilities, the profiles would most likely arise from Amanda, Laura, and Filomena, Meredith's three flatmates. Yet there were no reference samples taken from either Laura or Filomena, from what I can gather. So the whole laundry idea is speculation without support, IMHO.

About Me

I am a biochemist who specializes in the chemical modification of proteins and the synthesis of potential enzyme inhibitors. I am particularly interested in the chemistry of phosphorus and sulfur as it can be applied to biochemical problems.